1. Field of the Invention
The present invention relates to a head suspension for supporting a slider in a hard disk drive. In particular, the present invention relates to a method of simply and smoothly manufacturing a head suspension that is capable of suppressing off-track errors even when employed for a multi-arm assembly provided with a plurality of head suspensions.
2. Description of Related Art
A hard disk drive (HDD) incorporates a head suspension having a magnetic head slider (simply referred to as “slider”) to write/read data in a noncontact manner with respect to a disk-like recording medium rotated in the hard disk drive. The hard disk drive must employ a measure to prevent a data read/write error caused by an off-track error that the slider deviates from a target track on the recording medium.
In the hard disk drive, the head suspension provided with the slider forms a head gimbal assembly (HGA) and the head gimbal assembly is attached to a front end of an arm. The arm is turned around a turn axis with a voice coil motor (VCM) to position the slider onto a target track on the recording medium. If the recording medium or the head gimbal assembly vibrates out of an allowable range during the positioning of the slider onto a target track, a relative position between the voice coil motor and the target track changes to cause an off-track error.
A related art to suppress the off-track error is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2008-10063. This related art proposes a disk drive including a head suspension to support a slider and an arm to connect the head suspension to a turn shaft that turns the arm to move the slider over a recording surface of a disk-like recording medium. The arm is twisted in a direction from the turn shaft to the slider toward an outer circumference of the recording medium, so that the arm may bend and vibrate in a direction inclined in a radial direction of the recording medium with respect to a normal extended from the recording surface of the recording medium.
According to the related art, the head suspension is inclined according to the twisted arm, and therefore, the direction of bend or vibration between the arm and the head suspension inclines with respect to the normal extended from the recording surface of the recording medium. This reduces a peak value of off-track displacement of the slider that is determined by a skew angle and a bend/vibration direction, thereby keeping a slider positioning accuracy.
The related art manufactures a head suspension-arm assembly (simply referred to as “arm assembly”) by mechanically twisting the arm with a jig and attaching the head suspension to the arm, to reduce vibration components acting on the slider, as described in paragraph 0058 of the Japanese Unexamined Patent Application Publication No. 2008-10063. When manufacturing an arm assembly involving a plurality of arms according to the related art, arms other than an arm to be twisted interfere with the arm to be twisted, to hinder the twisting work. Namely, the twisting work of one arm must be carried out while avoiding the other arms. This makes the twisting work troublesome and increases the number of processes.